Ct0517.
In my view both types of feedback have a distinct sound in their "as built" states. Firstly I need to state two things.
1) I have a commercial interest in this topic, so you may want to take that into consideration.
2) How a machine is designed and how it is built are often completely different things. The designer makes a number of assumptions on the motor and feedback performance. Commercial reality can get in the way of these assumptions being realised.
This is what I hear.
Global feedback when carefully designed, but not properly put together, creates a tension in the music, a greyness. The music does not flow and does not properly connect with the listener. It is not servo overshoot, hunting or cogging. This sound is what the BD people talk about. This problem, in my opinion, can be largely removed.
Local feedback is softer and slower to respond to demand, it creates a slurring effect. The music is slightly blurred like a soft focus lens. Drive and dynamics are diminished.
My research into motors has shown that this can be reduced only slightly. The method of coupling the motor to the platter is immaterial, as this effect is built into the motor itself. This is why I have pushed my view that global feedback is neccessary, regardless of the drive method employed. It is the reduced "drive" that the DD people talk about.
Of the two, if I had to choose, I would take local. That was before I found a way to mitigate the problems of global feedback.
I hope that this helps.
In my view both types of feedback have a distinct sound in their "as built" states. Firstly I need to state two things.
1) I have a commercial interest in this topic, so you may want to take that into consideration.
2) How a machine is designed and how it is built are often completely different things. The designer makes a number of assumptions on the motor and feedback performance. Commercial reality can get in the way of these assumptions being realised.
This is what I hear.
Global feedback when carefully designed, but not properly put together, creates a tension in the music, a greyness. The music does not flow and does not properly connect with the listener. It is not servo overshoot, hunting or cogging. This sound is what the BD people talk about. This problem, in my opinion, can be largely removed.
Local feedback is softer and slower to respond to demand, it creates a slurring effect. The music is slightly blurred like a soft focus lens. Drive and dynamics are diminished.
My research into motors has shown that this can be reduced only slightly. The method of coupling the motor to the platter is immaterial, as this effect is built into the motor itself. This is why I have pushed my view that global feedback is neccessary, regardless of the drive method employed. It is the reduced "drive" that the DD people talk about.
Of the two, if I had to choose, I would take local. That was before I found a way to mitigate the problems of global feedback.
I hope that this helps.